Acid fluid loss due to wormholes is extremely difficult to control. It is generally considered to be the major factor limiting the effectiveness of acid fracturing treatments in carbonate formations. A new acid fracturing fluid has been developed to control fluid loss. With unique characteristics, this new fluid loss system is highly efficient and allows the acid to penetrate deeply into the fracture, resulting in superior stimulation.
This paper discusses the technical design and results obtained utilizing this new acid stimulation fluid in the Little Knife Field, Williston Basin, in North Dakota. Production comparisons show a substantial improvement in well performance from these wells following acid fracturing treatments. This new acid stimulation system improves live acid penetration in a naturally fractured carbonate reservoir, thus sustaining greater and longer production increases than prior stimulation treatments.